Diffractive lenses for vision correction

Abstract

Diffractive lenses for vision correction are provided on a lens body having a first diffractive structure for splitting light into two or more diffractive orders to different focal distances or ranges, and a second diffractive structure, referred to as a multiorder diffractive (MOD) structure, for diffracting light at different wavelengths into a plurality of different diffractive orders to a common focal distance or range. In a bifocal application, the first and second diffractive structures in combination define the base power for distance vision correction and add power for near vision correction of the lens. The first and second diffractive structures may be combined on the same surface or located on different surfaces of the lens. An optical element, such as a substrate or coating, may be integrated along one or both surfaces of the lens to provide the lens with smooth outer surface(s).

1. An ophthalmic lens comprising:
 a lens body having first and second surfaces; 
 a first diffractive structure for splitting light of different wavelengths into two or more diffractive orders to different focal distances or ranges; 
 a second diffractive structure for diffracting light into a plurality of different diffractive orders to a common focal distance or a substantially common focal distance, in which said first and second diffractive structures are located on the same or different ones of said first and second surfaces; and 
 said first and second diffractive structures in combination provide at least near and distance vision correction. 
 
   
   
     2. The lens according to  claim 1  wherein:
 said second diffractive structure has a second power; 
 said first diffractive structure has at least two different first powers in accordance with each of said diffractive orders of said first diffractive structure; 
 said lens has a base power for said distance vision correction in accordance with the combination of said second power of said second diffractive structure with one of said first powers of said first diffractive structure; and 
 said lens has an add power for said near vision correction in accordance with the combination of said second power of said second diffractive structure with another one of said first powers of said first diffractive structure. 
 
   
   
     3. The lens according to  claim 2  wherein said second power of said second diffractive structure mainly or entirely contributes in said combination with said first diffractive structure to said base power of said lens. 
   
   
     4. The lens according to  claim 1  wherein said second diffractive structure represents a multiorder diffractive structure characterized by a plurality of zones which define zone boundaries at which light incident on the diffractive structure experiences an optical phase shift, and which diffract light of each of said wavelengths in a different diffractive order, m, such that the magnitude of m≧1, to the focal distance or range for the diffractive structure. 
   
   
     5. The lens according to  claim 1  wherein said lens body has two sides providing said first and second surfaces, respectively, and said first surface is along one of said sides representing the front of said lens, and said second surface is along another one of said sides representing the back of said lens. 
   
   
     6. The lens according to  claim 1  wherein said lens body has two sides providing said first and second surfaces, respectively, and said second surface is along one of said sides representing the front of said lens, and said first surface is along another one of said sides representing the back of said lens. 
   
   
     7. The lens according to  claim 1  wherein said lens body has zero or near zero refractive power. 
   
   
     8. The lens according to  claim 1  wherein said lens body provides refractive power to said lens. 
   
   
     9. The lens according to  claim 1  further comprising an optical element, wherein one of said first surface or said second surface is integrated with said optical element, and said optical element provides said lens with a smooth outer surface. 
   
   
     10. The lens according to  claim 1  further comprising two optical elements, wherein said first surface and said second surface are integrated with a different ones of said optical elements, and said optical elements provides said lens with smooth outer surfaces. 
   
   
     11. The lens according to  claim 9  wherein said optical element represents one of a substrate or coating. 
   
   
     12. The lens according to  claim 10  wherein said optical elements each represent one of a substrate or coating. 
   
   
     13. The lens according to  claim 1  wherein said first and second diffractive structures are combined into a single diffractive structure along one of said first or second surfaces. 
   
   
     14. The lens according to  claim 13  further comprising an optical element integrated with said lens along said one of said first and second surfaces, and said optical element provides said lens with a smooth outer surface. 
   
   
     15. The lens according to  claim 1  wherein said lens is part of an intraocular implant. 
   
   
     16. The lens according to  claim 1  wherein said lens represents a contact lens. 
   
   
     17. The lens according to  claim 1  wherein said lens represents a spectacle lens. 
   
   
     18. The lens according to  claim 1  wherein at least one of said first and second diffractive structures corrects for astigmatism. 
   
   
     19. The lens according to  claim 1  wherein at least one of said first and second diffractive structures has refractive curvature which corrects for astigmatism. 
   
   
     20. The lens according to  claim 1  wherein said lens body is composed of a single optical element. 
   
   
     21. The lens according to  claim 1  wherein said lens body is composed of a plurality of optical elements integrated together. 
   
   
     22. The lens according to  claim 1  wherein said first diffractive structure splits light energy substantially equally in each of the orders of said first diffractive structure. 
   
   
     23. The lens according to  claim 1  wherein said first diffractive structure provides a certain amount of light into each of the orders of said first diffractive structure. 
   
   
     24. The lens according to  claim 1  wherein said first diffractive structure has a one of a blazed, sinusoidal, or square wave profile. 
   
   
     25. The lens according to  claim 1  wherein said lens body is sufficiently thin for use in IOL or contact lens applications. 
   
   
     26. The lens according to  claim 1  wherein said first diffractive structure splits light into two diffractive orders, and said first and second diffractive structures in combination provide a bifocal one of said lens with near and distance vision correction. 
   
   
     27. The lens according to  claim 1  wherein said first diffractive structure splits light into three diffractive orders, and said first and second diffractive structures in combination provide a trifocal one of said lens with near, intermediate, and distance vision correction. 
   
   
     28. A method for providing a bifocal ophthalmic lens having a base power and an add power comprising the steps of:
 selecting a first diffractive structure for the lens for diffracting light into a plurality of different diffractive orders to a common focal distance or or a substantially common focal distance in accordance with needed base power of the lens; and 
 selecting a second diffractive structure for the lens for splitting light into two or more diffractive orders to different focal distances or ranges in which the base power for distance vision correction and add power for near vision correction are in accordance with a combination of said first and said second diffractive structures. 
 
   
   
     29. The method according to  claim 28  wherein said lens has first and second surfaces, and said first and second diffractive structures are located on the same or different ones of said first and second surfaces. 
   
   
     30. The method according to  claim 28  wherein said first diffractive structure represents a multiorder diffractive structure characterized by a plurality of zones which define zone boundaries at which light incident on the diffractive structure experiences an optical phase shift, and which diffract light of each of said wavelengths in a different diffractive order, m, such that the magnitude of m≧1, to the focal distance or range for the diffractive structure. 
   
   
     31. The method according to  claim 28  wherein said lens has first and second surfaces, and said method further comprises the step of:
 adding to at least one surface of said lens an optical substrate providing a smooth outer surface to said lens. 
 
   
   
     32. The method according to  claim 28  further comprising the step of:
 selecting the body of said lens to have zero or approximately zero refractive power. 
 
   
   
     33. The method according to  claim 28  further comprising the step of:
 selecting the body of said lens to have refractive power. 
 
   
   
     34. The method according to  claim 28  wherein at least one of said first and second diffractive structures corrects for astigmatism. 
   
   
     35. The method according to  claim 28  wherein at least one of said first and second diffractive structures has refractive characteristics to correct for astigmatism. 
   
   
     36. An optical element comprising:
 a lens body having first and second surfaces; 
 a first diffractive structure for splitting light into two or more diffractive orders to different focal distances or ranges; 
 a second diffractive structure for diffracting light into a plurality of different diffractive orders to a common focal distance or a substantially common focal distance, in which said first and second diffractive structures are located on the same or different ones of said first and second surfaces; and 
 said first diffractive structure and said second diffractive structure in combination provide a plurality of different focal distances or ranges for vision correction at different distances or ranges. 
 
   
   
     37. The optical element according to  claim 36  wherein said different focal distances or ranges are two to provide a bifocal lens having near and far distance correction. 
   
   
     38. The optical element according to  claim 36  wherein said different focal distances or ranges are three to provide a trifocal lens having near, intermediate, and far distance correction.